A conventional bicycle rack is disclosed in FIGS. 6 and 7, and generally includes two tubes 61 including two sections which are connected with each other at angle. Two support bars 60 are respectively connected to the two tubes 61 for supporting bicycles thereon and two stretch plates 64 are connected between the two tubes 61 so as t o maintain the wide-open position of the rack. A locking device 65 locks the two stretch plates to avoid from being folded or collapsed. A connection device 62 includes two cups 63 which are connected to two respective insides of the two tubes 61 and each cup 63 has a recess 631 so as to embrace a sphere 70 connected to the vehicle. It is noted that there is a gap between the two cups 63 and the sphere 70 so that the rack shakes during transportation. In order to improve the shortcoming, a securing device 66 is disclosed in applicant's former patent application U.S. patent application Ser. No. 10/600,459, and includes a holding member 662 which is pivotably connected one of the two tubes 61 and has a hook portion at one end and a bolt 663 extends through the other end of the securing device 66. A ring 661 is pivotably connected to the other tube and is engaged with the hook portion of the holding member 62. The bolt 663 pushes the hook portion to be securely connected to the ring 661 so as to pull the two cups 63 together. Although the two cups 63 are pulled together by the securing device 66, the load of the bicycles on the supporting bars 60 which are located at a distance from the cups 63 shakes the two cups 63 and makes a lot of noise at the position where the two cups 63 clamp the sphere 70.
The present invention intends to provide a securing device for a bicycle rack wherein the sphere and the base for connecting the sphere are well secured so as to reduce the shaking during transportation.